//  Copyright hyperjumptech/grule-rule-engine Authors
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

package unique

import (
	"fmt"
	"sync"
	"time"
)

var (
	offset int64 = 0
	lastMS int64 = 0
	mutex  sync.Mutex
)

// NewID will create a new unique ID string for this runtime.
// Uniqueness between system or apps is not necessary.
func NewID() string {
	mutex.Lock()
	defer mutex.Unlock()
	millisUnix := time.Now().Unix()
	if lastMS == millisUnix {
		offset++

		return fmt.Sprintf("%d-%d", lastMS, offset)
	}
	lastMS = millisUnix
	offset = 0

	return fmt.Sprintf("%d-%d", lastMS, offset)
}
